Past and ongoing experimental studies are examining the potential benefits of synchronized coronary venous retroperfusson (SRP) treatment of acute myocardial ischemia. Combined systems including SRP integration with aortic counterpulsation and hypothermia are being developed in the hope of reversing severe ischemic derangements in cardiac function and reducing infarct size. Selected SRP systems, upgraded with professionally manufactured catheters and pumping equipment, will be subjected to verification tests using newly developed measurement methodologies. Effectiveness, safety and clinical applicability will be validated with two-dimensional echocardiography assessment of global and regional left ventricular function, further tagged microsphere study of myocardial perfusion, colloidal-carbon tracer technique to evaluate any vascular damage, myocardial radioimmuno assay CK MB to monitor effects of SRP on acute ischemia, and triphenyl-tetrazolium chloride staining for measurements of infarct size. A new retrograde coronary venous infusion treatment will be explored using various pharmacologic agents previously applied as systemic or intracoronary arterial interventions for treatment of acute ischemic injury. Optimization of SRP and operational criteria will be derived.